Minority teachers are quitting in droves across nine major cities, and education experts are asking why.

In a new report, "The State of Teacher Diversity in American Education," the Albert Shanker Institute found that in Boston, New York, Los Angeles, Chicago, Cleveland, New Orleans, Philadelphia, San Francisco, and Washington, D.C., the number of black teachers fell significantly from 2002 to 2012.

"There is this huge heralded success in the growth of recruitment rates for minority teachers but they've been undermined by these high quit rates," Richard Ingersoll, a professor at the University of Pennsylvania and contributor to the report, told NBC News. "My own conclusion is that we will not really close that gap until we go beyond recruitment and look at retention."

The distribution of black and Hispanic teachers across low- and high-income schools is one of the chief factors contributing to the attrition rate.

"Minority teachers are disproportionately employed in predominantly urban, predominantly poor, and predominantly high minority schools," Ingersoll said. "But such schools are not as attractive workplaces . . . and because minority teachers are the ones teaching at these schools, they have higher quit rates."

In Washington D.C., the number of white teachers more than doubled from 16 to 39 percent, and the number of black teachers decreased from 77 to 49 percent.

Ingersoll suggested that big, top-down government "turnaround" programs often imposed on failing schools often disempowers teachers, which in turn drives up their quit rates.

"With accountability, often you have a standardized curriculum that’s scripted and sometimes micromanaged," he said, The Washington Post reported. "There are certainly some positives, but the downside is it drives teachers nuts. . . . What I always suggest is that we hold people accountable for results but then get out of their way. It’s not the way we treat teachers in these large urban districts."